1. Field
Embodiments relate to a negative active material for a rechargeable lithium battery, a method of manufacturing the same, and a rechargeable lithium battery including the same.
2. Description of the Related Art
Lithium rechargeable batteries have recently drawn attention as a power source of small portable electronic devices. Lithium rechargeable batteries may use an organic electrolyte solution and may have twice the discharge voltage of a conventional battery using an alkali aqueous solution, and accordingly may have high energy density.
Positive active materials of a rechargeable lithium battery may include lithium-transition element composite oxides capable of intercalating lithium, e.g., LiCoO2, LiMn2O4, LiNi1-xCoxO2 (0<x<1), and the like.
As for negative active materials of a rechargeable lithium battery, various carbon-based materials, e.g., artificial graphite, natural graphite, and hard carbon, which may all intercalate and deintercalate lithium ions, have been used. Since graphite may have a low discharge potential relative to lithium, e.g., −0.2 V, a battery using the graphite as a negative active material may have a high discharge potential of 3.6 V and excellent energy density.
Furthermore, graphite may help ensure a long cycle life for a battery due to its outstanding reversibility. A carbon material having a crystalline structure that may be changed into graphite is referred to as soft carbon; and a carbon material that cannot be changed is referred to as hard carbon.
Generally, soft carbon may be prepared using processing residue of petroleum or coal and may be inexpensive. On the other hand, hard carbon may be relatively expensive because it is prepared by performing a heat treatment on resin. Since soft carbon may be more likely to be transformed into graphite than hard carbon, it has higher crystallinity than hard carbon.